Imagine footsteps that can charge mobile electronics. Scientists have created an innovative energy harvesting and storage technology that could reduce our reliance on the batteries in our mobile devices.
"Human walking carries a lot of energy," said Tom Krupenkin, one of the researchers, in a news release. "Theoretical estimates show that it can produce up to 10 watts per shoe, and that energy is just wasted as heat. A total of 20 watts from walking is not a small thing, especially compared to the power requirements of the majority of modern mobile devices."
The new energy-harvesting technology takes advantage of "reverse electrowetting." As a conductive liquid interacts with a nanofilm-coated surface, the mechanical energy is directly converted into electrical energy.
The reverse electrowetting method can generate usable power, but it requires an energy source with a reasonably high frequency-such as a mechanical source that's vibrating or rotating quickly. While the environment is full of low-frequency mechanical energy sources, high frequency was another matter.
To overcome this challenge, the researchers developed the "bubbler" method. This method combines reverse electrowetting with bubble growth and collapse. The bubbler device consists of two flat plates separated by a small gap filled with a conductive liquid. The bottom plate is covered with tiny holes through which pressurized gas forms bubbles. The bubbles grow until they're large enough to touch the top plate, which causes the bubble to collapse. This speed, repetitive growth pushes the conductive fluid back and forth and generates an electrical charge.
The new energy harvester could directly power mobile devices through a charging cable, or could be integrated with a broad range of electronic devices embedded in a show, such as a Wi-Fie hot spot.
The findings are published in the journal Scientific Reports.
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